1. Field of the Invention
The present invention pertains to a low contact nasal mask and to a pressure support system using such a mask to interface with the airway of a patient, and, in particular, to a low contact nasal mask that includes a one-piece, lightweight seal member defining a nose receiving cavity, a collar coupled to the seal member, and a conduit coupling member, and to a system for supplying a flow of gas to a patient that incorporates such a low contact nasal mask.
2. Description of the Related Art
There are numerous situations where it is necessary or desirable to deliver a flow of breathing gas non-invasively to the airway of a patient, i.e., without intubating the patient or surgically inserting an tracheal tube in their esophagus. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation. It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, which varies with the patient""s respiratory cycle, to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), or congestive heart failure. Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device, which is typically a nasal/oral mask, on the face of patient to interface the ventilator or pressure support device with the airway of the patient so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient.
Because such patient interface devices are typically worn for an extended period of time, a variety of concerns must be taken into consideration. For example, in providing CPAP to treat OSA, the patient normally wears the patient interface device all night long while he or she sleeps. One concern in such a situation is that the patient interface device is as comfortable as possible, otherwise the user may avoid wearing the interface device, defeating the purpose of the prescribed pressure support therapy. Interrelated with the patient comfort concern is the need for the patient interface device to provide an effective seal with the patient""s face to minimize leaks between the patient and the patient interface device throughout the therapy. Providing a good seal improves the operating efficiency of the pressure support or ventilatory therapy and also improves patient comfort by preventing or minimizing mask leaks, especially mask leaks that are directed toward the patient""s eyes, which tend to dry the eyes causing discomfort.
Accordingly, it is an object of the present invention to provide a nasal mask assembly that addresses the above identified concerns and that overcomes shortcomings of conventional patient interface devices. This object is achieved according to one embodiment of the present invention by providing a nasal mask assembly that includes a seal member defined from a unitary piece of elastomeric material. The seal member includes a nose receiving cavity, a first end portion, a second end portion generally opposite the first end portion. A first opening is defined in the first end portion to receive at least a portion of a nose of a patient such that nares of the patient communicate with the receiving cavity. The seal member also includes a neck portion defined in the second end portion and a second opening defined in the neck portion to provide an inlet for breathing gas from an external source and an outlet for the patient""s expelled gases. In addition, an outside diameter and an inside diameter of the seal member increase generally linearly from the second end portion to the first end portion to minimize contact of the seal member with a patient as well as dead space within the seal member. The nasal mask assembly also includes a collar coupled to the neck portion. The collar includes a plurality of headgear attachment points spaced apart from the seal member. In addition, the nasal mask assembly includes a conduit coupling member coupled to either the neck portion of the seal member and the collar for use in attaching the nasal mask assembly to a ventilator or pressure support device.
It is a further object of the present invention to provide a system for delivering a flow of gas to a patient that addresses the above identified concerns and that does not suffer from the shortcomings of conventional techniques. This object is achieved by providing a system for delivering a flow of gas to a patient that includes a gas flow generating device capable of producing a flow of gas and a conduit having a first end portion operatively coupled to the gas flow generating device and a second end portion. The conduit carries the flow of gas from the gas flow generating device. The system includes a nasal mask assembly operatively coupled to the second end portion of the conduit. The nasal mask assembly includes a seal member defined from a unitary piece of elastomeric material. The seal member includes a nose receiving cavity defined therein, a first end portion, and a second end portion generally opposite the first end portion. A first open is defined in the first end portion to allow at least a portion of the patient""s nose to be inserted into the nose receiving cavity so that the nares of the patient communicate with the nose receiving cavity. The seal member also includes a neck portion defined in the second end portion, and a second opening defined in the neck portion. The second opening communicates with the nose receiving cavity to provide an inlet for breathing gas from the gas flow generating device and an outlet for the patient""s expelled gases. In addition, an outside diameter of the seal member and an inside diameter of the seal member increase generally linearly from the second end portion to the end portion to minimize contact of the seal member with a patient and dead space.
The nasal mask assembly in the system for delivering a flow of gas to a patient further includes a collar coupled to the neck portion. The collar includes plurality of headgear attachment points spaced apart from the seal member. In addition, the nasal mask assembly a conduit coupling member having a first end portion coupled to the neck portion of the seal member or to the collar, and a second end portion coupled to the second end portion of the conduit.
These and other objects, features and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention.